FIG. 7 shows a schematic configuration of a main part of an exemplary conventional gear shaping machine (gear shaper) configured to manufacture a large external gear and a large internal gear through generating cutting of external teeth and internal teeth in a large workpiece by means of a pinion cutter.
As shown in FIG. 7, a cutter head 12 is disposed inside a housing 11, and a proximal side of the cutter head 12 is supported pivotally so that a distal side thereof may be swingable. A main spindle 13 is disposed in the cutter head 12 and penetrates therethrough with its distal side projected. The main spindle 13 is supported to be slidable in the axial direction, i.e., movable vertically, and also rotatable in the circumferential direction, relative to the cutter head 12. The main spindle 13 has its distal side projected from the inside of the housing 11, and a pinion cutter 14 is coaxially attached to the distal end.
The inner side of an annular external gear (unillustrated) is coaxially spline-coupled to the outer surface of the main spindle 13 so that rotation in the circumferential direction relative to the main spindle 13 may be restricted but movement in the axial direction relative to the main spindle 13 can be permitted. The external teeth on the external gear are meshing directly or indirectly with a drive gear (unillustrated) coaxially coupled to a drive shaft of an unillustrated drive source for rotation.
Specifically, when the drive shaft of the drive source for rotation is rotated, the main spindle 13 can be moved vertically relative to the cutter head 12 while being rotated in the circumferential direction through the drive gear, the external gear, and the like.
A distal side of a rod 15 is coupled to the proximal side of the main spindle 13 through a universal joint (unillustrated). A proximal side of the rod 15 is pivotally coupled to a distal side of a crank 16. A proximal side of the crank 16 is coupled to a drive shaft of an unillustrated drive source for vertical movement.
Specifically, as the drive shaft of the drive source for vertical movement is rotated, the crank 16 is rotated about its proximal side to swing its distal side. As transmitted through the rod 15 and the universal joint, the rotation can vertically move the main spindle 13 relative to the cutter head 12 together with the rotation in the circumferential direction.
A distal side of a rod 17 is coupled to the distal side of the cutter head 12 in such a way as to be pivotable in the same direction as that of the swing of the cutter head 12 about a swing shaft thereof. A proximal side of the rod 17 is pivotally coupled to a distal side of a link 18. A proximal side of the link 18 is coupled to a pivotally supported support shaft 19 through an unillustrated clamp mechanism. The link 18 can be rotated together with the support shaft 19 by closing the clamp mechanism, and can be rotated freely from the support shaft 19 by opening the clamp mechanism.
A proximal side of a lever 20 is integrally coupled to the support shaft 19. A cam 21 coupled to a drive shaft of an unillustrated drive source for relief is disposed on a distal side of the lever 20. The distal side of the lever 20 is biased by biasing means (unillustrated) to be always in contact with the cam surface of the cam 21.
Specifically, as the clamp mechanism is closed and the drive shaft of the drive source for relief is rotated, the lever 20 turns the support shaft 19 and swings the distal side of the link 18 in a way corresponding to the cam surface of the cam 21 having a predetermined profile, and thereby swings the distal side of the cutter head 12 through the rod 17. Accordingly, the position of the distal side of the main spindle 13, i.e. the position of the pinion cutter 14 can be swung and switched between a machining position at which the pinion cutter 14 contacts the workpiece and a relieved position at which the pinion cutter 14 is away from the workpiece.
Next, operations of the conventional gear shaping machine 10 configured as above will be described based on FIGS. 8 and 9.
As shown in FIG. 8, in a case of generating external teeth in a disk-shaped workpiece 1A, firstly, the clamp mechanism is opened, and the link 18 is pivoted about the support shaft 19 such that the distal side of the link 18 may be located at an upper, external-tooth machining position. Then, the clamp mechanism is closed to integrally fix the link 18 to the support shaft 19.
Subsequently, the drive source for rotation, the drive source for vertical movement, and the drive source for relief are actuated to rotate their drive shafts, and also an unillustrated table supporting the workpiece 1A is rotated. Along with the actuation of the drive source for rotation, the pinion cutter 14 is rotated through the gears and the main spindle 13. Moreover, along with the actuation of the drive source for vertical movement, the pinion cutter 14 is moved down in parallel with the axis of the workpiece 1A through the crank 16, the rod 15, the universal joint, and the main spindle 13. As a result, an external tooth is generated in a portion, in the circumferential direction, of the outer surface of the workpiece 1A (Parts A to C of FIG. 8).
Then, as the pinion cutter 14 is moved down to its lowermost position, the distal side of the lever 20 is pushed down along with the rotation of the cam 21 by the actuation of the drive source for relief. This turns the support shaft 19 and swings the distal side of the link 18 in a direction toward a radially outer side of the workpiece 1A (counterclockwise in FIG. 8), thereby moving the distal side of the cutter head 12 through the rod 17 in a direction away from the outer surface of the workpiece 1A (leftward in FIG. 8). As a result, the pinion cutter 14 is moved away from the outer surface of the workpiece 1A through the main spindle 13 so as to be located at the relieved position at the other side in the radial direction (left side in FIG. 8), and is also moved up along an arc path (relieving: Part D of FIG. 8).
Then, as the pinion cutter 14 is moved up to its uppermost position, the biasing force of the biasing means based on the rotation of the cam 21 brings the distal side of the lever 20 back to the initial position. This swings the distal side of the link 18 through the support shaft 19 in a direction toward a radially inner side of the workpiece 1A (clockwise in FIG. 8) and moves the distal side of the cutter head 12 through the rod 17 in a direction to approach the outer surface of the workpiece 1A (rightward in FIG. 8). As a result, through the main spindle 13, the pinion cutter 14 approaches the outer surface of the workpiece 1A so as to be located at the machining position at one side in the radial direction (right side in FIG. 8), and also the pinion cutter 14 is again moved down in parallel with the axis of the workpiece 1A. Along with this, the table is rotated, so that another external tooth is continuously generated in the outer surface of the workpiece 1A adjacently to the last generated external tooth (Parts A to C of FIG. 8).
By repeating the above-described operations subsequently, external teeth can be generated in the outer surface of the workpiece 1A over the entire circumferential length thereof.
On the other hand, as shown in FIG. 9, in a case of generating internal teeth in an annular workpiece 1B, firstly, the clamp mechanism is opened, and the link 18 is pivoted about the support shaft 19 such that the distal side of the link 18 may be located at a lower, internal-tooth machining position. Then, the clamp mechanism is closed to integrally fix the link 18 to the support shaft 19.
Subsequently, as in the case of external tooth machining, the drive source for rotation, the drive source for vertical movement, and the drive source for relief are actuated to rotate their drive shafts, and also an unillustrated table supporting the workpiece 1B is rotated. Along with the actuation of the drive source for rotation, the pinion cutter 14 is rotated through the gears and the main spindle 13. Moreover, along with the actuation of the drive source for vertical movement, the pinion cutter 14 is moved down in parallel with the axis of the workpiece 1B through the crank 16, the rod 15, the universal joint, and the main spindle 13. As a result, an internal tooth is generated in a portion, in the circumferential direction, of the inner surface of the workpiece 1B (Parts A to C of FIG. 9).
Then, as the pinion cutter 14 is moved down to its lowermost position, the distal side of the lever 20 is pushed down along with the rotation of the cam 21 by the actuation of the drive source for relief. This turns the support shaft 19 and swings the distal side of the link 18 in a direction toward a radially inner side of the workpiece 1B (counterclockwise in FIG. 9), thereby moving the distal side of the cutter head 12 through the rod 17 in a direction away from the inner surface of the workpiece 1B (rightward in FIG. 9). As a result, the pinion cutter 14 is moved away from the inner surface of the workpiece 1B through the main spindle 13 so as to be located at the relieved position at the one side in the radial direction (right side in FIG. 9), and is also moved up along an arc path (relieving: Part D of FIG. 9).
Then, as the pinion cutter 14 is moved up to its uppermost position, the biasing force of the biasing means based on the rotation of the cam 21 brings the distal side of the lever 20 back to the initial position. This swings the distal side of the link 18 through the support shaft 19 in the direction toward the radially inner side of the workpiece 1B (clockwise in FIG. 9) and moves the distal side of the cutter head 12 through the rod 17 in a direction to approach the inner surface of the workpiece 1B (leftward in FIG. 9). As a result, through the main spindle 13, the pinion cutter 14 approaches the inner surface of the workpiece 1B so as to be located at the machining position at the other side in the radial direction (left side in FIG. 9), and also the pinion cutter 14 is again moved down in parallel with the axis of the workpiece 1B. Along with this, the table is rotated, so that another internal tooth is continuously generated in the inner surface of the workpiece 1B adjacently to the last generated internal tooth (Parts A to C of FIG. 9).
By repeating the above-described operations subsequently, internal teeth can be generated in the inner surface of the workpiece 1B over the entire circumferential length thereof.
Thus, in the gear shaping machine 10, external teeth can be generated in the disk-shaped workpiece 1A, and internal teeth can be generated in the annular workpiece 1B, as a matter of course. In addition to this, the link 18 may be pivoted to locate the distal side of the link 18 at the upper, external-tooth machining position or the lower, internal-tooth machining position, and therefore the machining position and the relieved position of the pinion cutter 14 at the one and the other sides in the radial direction can be switched between the case of external tooth generation (when the right side of the pinion cutter 14 in FIG. 8 is the machining position) and the case of internal tooth generation (when the left side of the pinion cutter 14 in FIG. 9 is the machining position). Accordingly, the position of the workpiece 1A for external tooth generation and the position of the workpiece 1B for internal tooth generation relative to the main spindle 13 do not need to differ greatly from each other. Even when the workpieces 1A and 1B are large (e.g. several meters in diameter), a single machine can perform both external tooth generation and internal tooth generation without a major overhang of the main spindle 13 and the like.